Problem: Is ${250120}$ divisible by $4$ ?
Answer: A number is divisible by $4$ if the last two digits are divisible by $4$ . [ Why? We can rewrite the number as a multiple of $100$ plus the last two digits: $ \gray{2501} {20} = \gray{2501} \gray{00} + {20} $ Because $250100$ is a multiple of $100$ , it is also a multiple of $4$ So as long as the value of the last two digits, ${20}$ , is divisible by $4$ , the original number must also be divisible by $4$ Is the value of the last two digits, $20$ , divisible by $4$ Yes, ${20 \div 4 = 5}$, so $250120$ must also be divisible by $4$.